Biomedical subjects

D S Sacks

Publications and source records attributed to D S Sacks.

3 recordsLinked to original sources

PubMed1997

Polarization anatomy of a kainic acid seizure.

Slow voltage-sensitive dyes work by accumulating in brain tissue and report the average membrane potential of neurons and glia. The voltage-sensitive dye diO-C2-5 was used to monitor the polarization state of 27 brain structures in the rat during a systemically induced, behaviorally mild, kainic acid seizure using a 20 s recording period. The effects of the anesthetic agent used in the experiment were minimized by delaying the dye injection and seizure mapping for one day. Eleven areas were depolarized during the seizure, but 16 other areas did not change their polarization state compared to controls. The effects of pentobarbital appear to have no measurable effect on seizure propagation once the animal has behaviorally recovered from the anesthesia. The technique allows for mapping areas of seizure involvement with a unique combination of spatial and temporal resolution.

Adjuvants, Anesthesia↗

PubMed1992

In vivo mapping of drug-induced seizures with voltage-sensitive dye.

The voltage-sensitive dye diO-C2-5 was used to produce an in vivo map of the membrane potential in two types of seizures. Mild limbic seizures were induced in rats with kainic acid; clonic convulsive seizures were induced with bicuculline. Kainic acid animals showed various levels of neural depolarization during their seizures in limbic, thalamic, cortical, and brainstem sites. The bicuculline animals showed uniformly greater levels of neural depolarization during their seizures. The magnitude of these changes relative to controls varied across seizure models and reflected the different underlying neural mechanisms for each model. The ability of the technique to capture local electrical events provides a new tool in which to explore brain activity.

Animals↗

PubMed1992

Seizure circuit analysis with voltage sensitive dye.

Voltage sensitive dye was used to produce a map of average membrane polarization for the purpose of analysing the circuitry involved in seizures. Dorsal hippocampus, ventral hippocampus, entorhinal cortex, substantia nigra and occipital cortex were selected to calculate the relative changes in polarization. Rats were induced with bicuculline to have convulsive seizures and mild limbic seizures with kainic acid. A 20 second sample of these seizures were recorded using the voltage sensitive dye. Control animals showed a relatively uniform polarization state in the five brain areas. The bicuculline seizure produced hyperpolarization in all five areas. The magnitude of the hyperpolarization varied among the regions to produce a distinctive pattern. The kainic acid seizure produced depolarization in the four limbic areas. The magnitude of the depolarization also varied, producing a different pattern compared with bicuculline or control. Future applications of this technique in animal models could help identify those areas in the brain which regulate seizure propagation, and the anatomical loci in which antiepileptic drugs interfere with this propagation. Ultimately, human applications would include linking voltage sensitive dyes with paramagnetic or positron emitting traces so that epileptic processes could be visualized using magnetic resonance imaging or positron emission computed tomography.

Animals↗